Method of manufacturing a nonvolatile semiconductor memory device

Abstract

Nonvolatile semiconductor memory devices and methods for manufacturing thereof, which provide inhibiting the shortcutting of the channel due to the creation of the bird's beak to promote the manufacturing of the devices with higher-density or higher-integration, lowering the operation voltage and improving the characteristics of maintaining the electric charge, without complicating the manufacturing process. Immediately after forming ONO films comprising a first silicon oxide film, a second silicon nitride film and a third silicon oxide film on a silicon substrate, a silicon layer is formed, and then, arsenic ions are implanted over the silicon layer and/or ONO films to form a bit line, and a second electrical conductive layer is deposited while remaining the silicon layer to form a word line comprising a dual layer structure of two electrical conductive layers.

1 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film on a semiconductor substrate;    forming a first electrical conductive film on said insulating film; and    implanting an impurity into said semiconductor substrate through at least said insulating film to form a diffusion layer on a surface of said semiconductor substrate.    
   
   
       2 . The method according to  claim 1 , wherein said impurity is implanted through said first electrical conductive film and said insulating film in said implanting the impurity.  
   
   
       3 . The method according to  claim 1 , further comprising selectively removing said first electrical conductive film before said implanting the impurity, wherein said impurity is implanted through said insulating film into the region of said semiconductor substrate where said first electrical conductive film thereon is removed in said implanting the impurity.  
   
   
       4 . The method according to  claim 1 , wherein said first electrical conductive film on said diffusion layer is, or said insulating film and said first electrical conductive film are transformed by thermal oxidization or radical oxidization to an oxide film.  
   
   
       5 . The method according to  claim 1 , wherein said insulating film comprises ON films or ONO films, said ON films being formed by depositing a silicon oxide film and subsequently depositing a silicon nitride film thereon, and said ONO films being formed by depositing a silicon oxide film, subsequently depositing a silicon nitride film thereon and subsequently depositing a silicon oxide film thereon.  
   
   
       6 . The method according to  claim 5 , wherein said impurity is implanted through at least said silicon nitride film of said ON films or said ONO films to transmute parts of said silicon nitride film formed on said diffusion layers.  
   
   
       7 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film on a silicon substrate;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    implanting via said patterned mask an impurity thereto through said first electrical conductive film and said insulating film to form a diffusion layer on a surface of said silicon substrate for forming a bit line;    removing said patterned mask;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.    
   
   
       8 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    removing an exposed portion of said first electrical conductive film via said patterned mask;    implanting via said patterned mask an impurity thereto through said insulating film to form a diffusion layer on a surface of said silicon substrate for forming a bit line;    removing said patterned mask;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.    
   
   
       9 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    implanting via said patterned mask an impurity thereto through said first electrical conductive film and said insulating film to form a diffusion layer on a surface of said silicon substrate for forming a bit line;    oxidizing the exposed portion of said first electrical conductive film by thermal oxidization or radical oxidization to form an oxide film on said insulating film;    removing said patterned mask;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.    
   
   
       10 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    implanting via said patterned mask an impurity thereto through said first electrical conductive film and said insulating film to form a diffusion layer on a surface of said silicon substrate for forming a bit line;    oxidizing the exposed portion of said first electrical conductive film and said insulating film underlying thereof by thermal oxidization or radical oxidization to form an oxide film on said diffusion layer;    removing said patterned mask;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.    
   
   
       11 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    forming a sidewall film having a predetermined thickness on a sidewall of said patterned mask by depositing a silicon nitride film and etching back thereof;    implanting via said patterned mask an impurity thereto through said first electrical conductive film and said insulating film to form a diffusion layer on a surface of said silicon substrate for forming a bit line, an opening width of said patterned mask being limited by said sidewall;    removing said patterned mask and said sidewall film;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.    
   
   
       12 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    removing said exposed first electrical conductive film via said patterned mask to expose said insulating film;    implanting via said patterned mask an impurity through said insulating film thereto to form a diffusion layer on a surface of said silicon substrate for forming a bit line;    removing said exposed insulating film via said patterned mask;    forming an oxide film on at least said diffusion layer and sidewalls of said insulating film and said first electrical conductive film, said oxide film having a thickness that is less than the thickness of said insulating film;    removing said patterned mask;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.    
   
   
       13 . A method for manufacturing a nonvolatile semiconductor memory device, comprising: 
 forming an insulating film;    forming a first electrical conductive film on said insulating film;    forming a patterned mask on said first electrical conductive film;    removing said exposed first electrical conductive film and said insulating film underlying thereof via said patterned mask;    forming an oxide film on at least said diffusion layer and on sidewalls of said insulating film and said first electrical conductive film, said oxide film having a thickness that is less than the thickness of said insulating film;    implanting via said patterned mask an impurity thereto through said oxide film to form a diffusion layer on a surface of said silicon substrate for forming a bit line;    removing said patterned mask;    forming a second electrical conductive film on said first electrical conductive film; and    forming a word line comprising a dual-layer structure of said first electrical conductive film and said second electrical conductive film.